An Unexpected Mcvaughia (Malpighiaceae) Species from Sandy Coastal Plains in Northeastern Brazil

Transcription

1 Systematic Botany (2015), 40(2) Copyright 2015 by the American Society of Plant Taxonomists DOI / X Date of publication July 23, 2015 An Unexpected Mcvaughia (Malpighiaceae) Species from Sandy Coastal Plains in Northeastern Brazil André M. Amorim 1,2,3,4 and Rafael F. Almeida 3 1 Universidade Estadual de Santa Cruz, Departamento de Ciências Biológicas, Rodovia Ilhéus-Itabuna, , Ilhéus, Bahia, Brazil. 2 Herbário Centro de Pesquisas do Cacau, CEPEC, Rodovia Ilhéus-Itabuna, , Ilhéus, Bahia, Brazil. 3 Universidade Estadual de Feira de Santana, Departamento de Ciências Biológicas, Programa de Pós-Graduação em Botânica, Av. Transnordestina, , Feira de Santana, Bahia, Brazil. 4 Author for correspondence (amorim.uesc@gmail.com) Communicating Editor: Chuck Bell Abstract Mcvaughia sergipana is described and illustrated. It differs from the single other species in the genus by the metallic-sericeous, and soon deciduous indumentum on the leaves, small glands scattered throughout the lamina, lateral cincinni with 1 2 flowers, and larger posterior petal. This new species is only known from sandy coastal plains in Sergipe State, Brazil, and is critically endangered. Its distribution is estimated to be less than 100 km 2 in a region of extremely disturbed environments. Keywords Atlantic Forest, Burdachia, Glandonia, Malpighiales, Sergipe State. Mcvaughia W. R. Anderson is a genus of Malpighiaceae endemic to northeastern Brazil (Anderson 1979), previously with only a single species: M. bahiana W. R. Anderson. The genus can be easily recognized by its shrubby habit, anterior petals nested inside one another, horseshoe-shaped anthers, and nuts with the epicarp twisted a 180-degree angle (Anderson 1979). Mcvaughia bahiana is found only in dry, open habitats of Caatinga (dryland) vegetation in northeastern Bahia State, Brazil (Anderson 1979), with only a few collections near the type locality. Mcvaughia represents an intriguing case of geographic disjunction within Malpighiaceae, due to its placement as sister-group to two Amazonian lineages, Burdachia A. Juss. and Glandonia Griseb., the so called Mcvaughia clade (Davis and Anderson 2010). These two latter genera are widely distributed throughout the Amazon Basin with Burdachia reaching the Guyanas, but absent in northeastern Brazil, from where Mcvaughia was first described 35 yr ago (Anderson 1979). During recent fieldwork, and through examination of collections at the most important herbaria in Sergipe State, Brazil, we were surprised by finding a new species of Mcvaughia. This species is apparently endemic to sandy coastal plains (restinga vegetation) in the Atlantic Forest biome. With one exception, all specimens of the new species described here were collected within the last four years. Materials and Methods The description and illustrations of the new species presented here are based on field collections and studies of herbarium specimens. Information concerning the plant height, habit, presence of color on the hairs, lamina surface, glands, sepals, petals, fruits, and other informative traits were noted while examining fresh material in the field or transcribed from the collection labels of the herbarium specimens. Descriptions, morphological illustrations, and maps are based only on plant material from field collections and additional specimens from the ALCB, ASE, CEPEC, and HUEFS herbaria. The maps were generated using Arcgis software (ESRI 2010) and the geographical coordinates obtained from herbarium specimens. Taxonomic Treatment Mcvaughia sergipana Amorim & R. F. Almeida, sp. nov. TYPE: BRAZIL. Sergipe: Mun. Pirambu, Estrada para Lagoa Redonda, restinga sobre tabuleiro, S, W, 96 m, 7 Oct 2013 (fl, fr), A. M. Amorim, L. C. Marinho, & R. F. Almeida 8393 (holotype: CEPEC!; isotypes: ASE!, HUEFS!, MBM!, NY!, MICH!, P!, RB!, SP!). Mcvaughia sergipana differs from M. bahiana by the former having the abaxial leaf surface sericeous, lateral cincinni with 1 2 flowers, and posterior petal limb mm long, with the latter having the abaxial leaf surface densely tomentose or lanuginose, lateral cincinni with 2 7 flowers, and the posterior petal limb ca. 3 mm long. Shrubs m tall, basal stems 4 8 cm diam.; stipules 3 5 mm long, densely sericeous, persistent. Leaves mostly straight, opposite; petiole (0.3 ) cm long, canaliculate, initially sericeous and later glabrescent, eglandular; lamina of larger leaves ( 12) (2.7 )3 5.8( 6.5)cm, chartaceous to subcoriaceous, elliptic to ovate, rarely elliptic-lanceolate, apex acute or slightly acuminate, base acute or cuneate, margins slightly revolute, rarely flattened; lamina with 2 prominent abaxial glands at base, on each side of the midrib, with other smaller impressed glands scattered throughout lamina, adaxial surface green, initially sericeous and very soon glabrescent, abaxial surface initially densely metallic sericeous and soon glabrescent, thinly sericeous proximally on and near midrib and veins. Inflorescence a terminal raceme of cincinni, (6.5 ) cm long, lateral cincinni, opposite to subopposite, rachis striated, densely sericeous, with brown hairs, 1 2 flowers per cincinnus; bract mm long, lanceolate, spreading; bracteoles mm long, triangular, subopposite, spreading, one having a conspicuous green gland at base; peduncle 4 5 mm long, sparsely sericeous; pedicel 2 3 mm long, sparsely sericeous. Flowers with sepals carinate, covering most of the androecium, apex rounded, margin short ciliate, adaxial surface glabrous, abaxial surface sericeous, glabrescent near the margin; lateral 4 sepals biglandular, anterior sepal eglandular, glands ca mm, yellow, obovate; petals golden yellow, soon deciduous; anterior lateral petals orbicular, cucullate, limb ca. 4 margin erose, eglandular, claws ca mm; posterior lateral petals obovate, spreading, limb mm, margin erose, eglandular, claws ca mm; posterior cm, brown, straight, 5 mm,

2 SYSTEMATIC BOTANY [Volume 40 Fig. 1. Mcvaughia sergipana. A. Flowering branch. B. Abaxial surface of the lamina. C. Detail of the abaxial surface of the lamina. D. Detail of laminar glands and hairs. E. Lateral cincinnus general view. F. Detail of the anterior sepal showing the carina in the middle, abaxial surface. G. Petals, laid out, disposition at anthesis. H. Androecium, laid out, abaxial view, the stamen first from right opposite the anterior sepal, the stamen third from left opposite the posterior lateral petal. I. Gynoecium, posterior style in the middle, lateral view. J. Nut, lateral view. Scale bar: A C: 1 cm, D: 0.5 mm, E, G, and H: 2 mm, F and I: 1 mm, J: 1.5 mm. Based on A. M. Amorim et al

3 2015] AMORIM AND ALMEIDA: AN UNEXPECTED MCVAUGHIA Fig. 2. Mcvaughia sergipana. A. Flowering branch. B. Leaf showing a metallic-sericeous surface. C. Inflorescence with buds and flowers at anthesis. D. Detail of flowers. E. Detail of old flowers and nuts. F. Habitat on a sandy coastal plain (restinga vegetation). Based on A. M. Amorim et al

4 SYSTEMATIC BOTANY [Volume 40 petal obovate to orbicular, suberect, erose, limb mm, 2 3 pairs of reniform glands at the base of limb, proximal pair larger, claws ca. 0.5 mm. Stamens free at base, filaments mm long., cylindrical, thicker at base, horse-shaped anthers, ca mm, glabrous; stamens opposite the posterior-lateral petals slightly curved towards the apex; stamens opposite the posteriorlateral sepals and the posterior petal reduced to staminodes; stamens opposite the posterior lateral sepals covered by sepals, filaments ca mm long, triangular, anthers aborted; stamen opposite the posterior petal not covered by sepals, exserted, pointing towards the posterior petal, filament mm. Ovary sericeous; styles 3, erect, ca mm, cylindrical, parallel, glabrous, anterior style slightly smaller than posterior ones; stigma lateral, circular. Nuts 7 9( 11) mm, green, cylindrical, slightly twisted, apex with persistent styles, base ca. 1.0 mm long, triangular, anther mm, ovoid, densely Fig. 3. Map of the geographic distributions of Mcvaughia species. The square shows M. sergipana and circles M. bahiana.

5 2015] AMORIM AND ALMEIDA: AN UNEXPECTED MCVAUGHIA rugose when dried, sparsely sericeous, with brown hairs, with 2 chambers, proximal chamber containing the seed, distal chamber containing an oily substance; seed globose, rugose; embryo not seen. Figures 1, 2. Additional Specimens Examined BRAZIL. Sergipe: Mun. Pirambu, tabuleiros arenosos, 20 Dec 1978 (fl), M. Fonseca, without number (ASE 0671); caminho para Lagoa Redonda, restinga, 17 May 2011 (fl), M. C. Santana et al. 911 (ASE); Lagoa Redonda, 1 Nov 2011 (fl), E. A. Melo et al. 13 (ASE); ambiente de tabuleiro/restinga, S, W, 9 May 2013 (fl, fr), G. M. A. Matos et al. 270 (ASE, CEPEC). Distribution and Habitat Mcvaughia sergipana appears to be endemic to sandy coastal plains (restinga vegetation) within the Atlantic Forest domain of Sergipe State, Brazil (Fig. 3). Conservation According to IUCN (2001) criteria, Mcvaughia sergipana is considered critically endangered (CR B1ab) as its distribution is restricted to an area of less than 100 km 2, to not more than one locality, and occurs in an extremely fragmented area. Phenology Plants were found in flower in May, October, and December; in fruit in May and October. Etymology The specific epithet refers to its occurrence in Sergipe State, Brazil. Taxonomy Mcvaughia sergipana can be distinguished from M. bahiana by the following combination of characters: leaves with petiole cm long (vs. petiole cm long), lamina cm long (vs. lamina cm long), abaxial surface with two pairs of glands near base and many impressed glands scattered throughout the lamina (vs. abaxial surface with two pairs of glands near base), abaxial surface initially densely metallic-sericeous and soon glabrescent (vs. abaxial surface densely tomentose or lanuginose with ferruginous indumentum, later glabrescent), lateral cincinni with 1 2 flowers (vs. lateral cincinni with 2 7 flowers), posterior petal mm (vs. posterior petal ca mm), and ovary mm tall (vs. ovary mm tall). Additionally, the inflorescence of M. sergipana is longer, it has greater numbers of lateral cincinni, and its nuts are larger. Mcvaughia appears to be restricted to sandy soils within the Tucano and Sergipe-Alagoas sedimentary basins, with a different species being endemic to each area occurring in distinct habitats (caatinga vs restinga). Mcvaughia bahiana, the only other known species of Mcvaughia, also occurs on sandy soils in the Tucano Sedimentary Basin. This area represents a conspicuous phytogeographic zone within the Caatinga vegetation domain, with a biota distinct from other Caatinga areas that grow over crystalline shield geological formations and holds endemics for some angiosperm families (Cardoso and Queiroz 2007) (Fig. 3). Mcvaughia is a sister-group of Burdachia and Glandonia (Mcvaughia clade), both Amazonian lineages usually found growing along riversides throughout the Amazon Basin (Burdachia is also found in Guyana), with water-dispersed fruits (Davis and Anderson 2010). Davis et al. (2004, 2014) estimated myr for the origin of the Mcvaughia clade, but myr for the diversification of most of its current lineages. Numerous marine transgression events occurred along the Brazilian coast during this epoch (Oligo- Miocene boundary) (Rossetti et al. 2013) that may have had key roles in the evolutionary and biogeographical history of the Mcvaughia clade. Acknowledgments. We thank Klei Sousa for the drawings, Dra. Ana Paula Prata, the curator of ASE, and her staff for their assistance while consulting the herbarium collections and Lucas C. Marinho for the graphical support. AMA received financial support from CNPq (Produtividade em Pesquisa, grant # /2012 4; Reflora Malpighiales Project, grant # /2010 0; and Universal Project, grant # /2013 9). RFA was sponsored by a FAPESB doctoral fellowship (grant # BOL0584/2013). Literature Cited Anderson, W. R Mcvaughia, a new genus of Malpighiaceae from Brazil. Taxon 28: Cardoso, D. B. O. S. and L. P. Queiroz Diversidade de Leguminosae nas Caatingas de Tucano, Bahia: implicações para a fitogeografia do semi-árido do nordeste do Brasil. Rodriguesia 58: Davis, C. C., P. W. Fritsch, C. D. Bell, and S. Mathews High latitude Tertiary migrations of an exclusively tropical clade: Evidence from Malpighiaceae. International Journal of Plant Sciences 165: S107 S121. Davis, C. C., H. Schaefer, Z. Xi, D. A. Baum, M. J. Donoghue, and L. J. Harmon Long-term morphological stasis maintained by a plant pollinator mutualism. Proceedings of the National Academy of Sciences USA 111: Davis, C. C. and W. R. Anderson A complete generic phylogeny of Malpighiaceae inferred from nucleotide sequence data and morphology. American Journal of Botany 97: ESRI-Environmental Systems Research Institute ArcGIS, version Redlands, California: Environmental Systems Research Institute. IUCN IUCN red list categories and criteria: Version 3.1. Gland, Switzerland and Cambridge, U. K.: IUCN Species Survival Commission. Rossetti, D. F., F. H. R. Bezerra, and J. M. L. Dominguez Late Oligocene-Miocene transgressions along the equatorial and eastern margins of Brazil. Earth-Science Reviews 123: